1. Field of the Invention
This invention relates to medical diagnostic and therapeutic methods and, in particular, to a method for cannulating blood vessels, including, but not limited to retinal blood vessels, such that a medication may be injected or a quantity of fluid removed from the blood vessel. Alternatively, a catheter, wire or stent may be placed through the cannula to treat or diagnose an area remote from the insertion site.
2. Description of Related Art
The cannulation of a retinal blood vessel is difficult as the lumen of the blood vessels is less than 200 microns in size. The present day ocular instruments are too large to cannulate the vessel and the dexterity required to maintain the cannula within the blood vessel for several minutes is not commonly available. The piercing of a blood vessel elsewhere in the body to inject medications, perform surgical procedures or remove blood for analysis and treatment is commonly performed. It is therefore, to the effective resolution of the aforementioned problems and shortcomings that the present invention is directed.
Furthermore, perforating a blood vessel or other structure to withdraw blood, inject or infuse a substance into the blood vessel, thread a catheter, wire, fiber or other device into a blood vessel are established procedures in medicine. It is common practice to apply pressure for a variable length of time to the perforation or cannulation site once the needle, cannula, catheter, wire, etc. is withdrawn. Generally if the perforation site is in a small blood vessel near the skin surface and/or a small gauge needle is used the application of pressure should minimize the extravasation of blood from the puncture site. However, in situations where the blood vessel or structure is large or deep to the skin surface, or a large bore needle is used, or the patient has a bleeding proclivity from a blood abnormality or uses a medication that delays blood clotting, significant hemorrhaging may occur once the device is removed from the blood vessel or structure. This may happen despite the application of pressure for a limited amount of time or despite the application of a pressure bandage.
Accordingly, it is an object of this invention to provide a microcannula or micropipette whose lumen is small enough to be safely placed within the lumen of a retinal blood vessel and by its configuration is parallel to the lumen when placed through a standard sclerotomy site, as commonly used in vitreoretinal surgery.
It is another object of this invention to provide, by its configuration and method of attachment, a stable support such that the micropipette may be securely held within the blood vessel so that subsequent maneuvers may be safely accomplished.
It is still another object of this invention to provide a micromanipulator such that the micropipette may be remotely advanced to perforate the retinal blood vessel.
It is yet another object of this invention to provide a portable device that may be easily attached to a standard operating surgical wrist rest and is stable in its “X”, “Y” and “Z” planes.
It is a further object of this invention to provide a device that, by its configuration and method of attachment, does not inhibit the surgeon's view when using an operating microscope or otherwise interfere with the use of the operating microscope.
It is yet another object of this invention to provide a safe method such that the surgical procedure may be performed.
Another object of the invention is to provide a device that by the nature of its design will lessen or eliminate the amount of hemorrhage that occurs when a needle, cannula, catheter, wire, stent, fiber or other device is removed from a blood vessel or other structure.
Another object of this invention is to provide a device that can easily perforate a designated blood vessel.
Another object of this invention is to provide a device that by its nature and design is compatible with existing syringes, cannulas, catheters, etc.
Another object of this invention is to provide an ocular implant needle.